Control system



Oct. 5, 1943. fiw 2,331,256

common SYSTEM Filed Feb. 26. 1941 Q m 3* Y WITNESSES! INVENTOR Patented Oct. 5, 1943 UNlTED STATES PATENT OFFICE conrii rf siisrm Thelbert L. Weybrew, Edgewood, Pa,v assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pee, a corporation of Pennsylvania 3 Claims.

My invention relates, generally; to control systems and, more particularly; to. systems for con trolling the operation of Diesel or gas-electric locomotives.

The traction motors of a Diesel-electric loco,- motive are supplied with electric energy by a separately excited generator driven by the Diesel engine. supplied by an exciter also driven by the engine. The exciter may be partially separately excited from a storage battery and partially self-excited. The separately excited field is, continuously energized from the battery While the locomotive is in operation. Therefore, the exciter alway develops a voltage which, if applied to the generator field winding at the same time that the traction motors are connected to the generator, results in a rapid start of the locomotive from standstill. Such rapid starts are considered desirable in normal switching service. However, when locomotives of this type are utilized in switching occupied Pullman cars, it is desirable to start more smoothly in order to avoid discomfort to the passengers. Furthermore, it is desirable. that the control system be not unduly complicated in order to lower the initial cost of the equipment as well as the maintenance expense.

An object of my invention, generally stated, is to provide a control system for a Diesel-electric locomotive which shall be simple and efiicient in operation and which may be economically manufactured and installed.

A more specific object of my invention is to provide for smooth operation of a Diesel-electric locomotive both during starting from standstill and during transition from series to parallel operation of the motors.

Other objects of my invention will be explained fully hereinafter or will be apparent to those skilled in the art.

In accordance with one embodiment of my inthe traction motors have started to develop tractive effort in proportion to the relatively low generator voltage. Likewise, the resistor shunting switch is opened to reduce the generator voltage during transition from series to parallel operation of the motors and its reclosing after transition is Excitation current for th generator is.

= therein comprises a pair of traction motors ill and H, a generator 12 for supplying current to the motors l0 and I l an exciter I 3 and an engine I 4 for driving the generator 12 and the exciter l3. The engine [4 may be either a Diesel or a gas engine and is provided with a throttle l5 for controlling the supply of fuel to the engine. The generator I2 is provided with a field winding it which is energized by the exciter l3. As shown. the exciter I3 is provided with a field winding i! which is energized by a battery l8 when a switch I9 is closed. If desired, the exciter I3 may also be provided with a self-excited field winding (not shown).

A variable resistor 2| is provided in the cir cult for the field winding ll to adjust the excitation current for the exciter i3. Reversing switches 22 and 23 ar provided for reversing the current in the field windings 24 and 25 of the motors IB and II, respectively.

In accordance with the usual practice, a switch S is provided for connecting the motor across the generator l2 in series-circuit relation and switches PI and P2 are provided for connecting the motors Ill and H in parallel-circuit relation.

. A controller MC, which may be of the drum type,

is provided for controlling the operation of the switches S, PI and P2.

In order to reduce the voltage developed by the generator 12 while the engine M is idling and also during the transition of the motors It and i E from series to parallel operation, a resistor 25 is inserted in the circuit for the field winding l5 oi the generator I2. A switch CF is provided for shunting the resistor 26 when full voltage of the generator I! is desired. As explained herein before, the operation of the switch GF is so con trolled by interlocks provided on the switches S and P2 that theclosing of the switch CF to shunt the resistor 25 from the field winding circuit is delayed until the motors have started to develop a tractive effort at the reduced voltage of the generator. The reclosing of the switch GF after the transition period is also delayed, as will be explained more fully hereinafter. In this manner, a smooth starting of the locomotive from standstill is provided and also a smooth transition from series to parallel operation, since the tractive effort and hence the locomotive movement builds up gradually.

In order that the functioning of the foregoing apparatus may be more clearly understood, the operation of the system will now be described in detail. Assuming that the engine M has been started in the usual manner, the locomotive may be put into operation by closing the switch L! to energize the field winding H. The controller MC is then actuated to the series position and the throttle [5 opened to increase the supply of fuel to the engine M. It will be noted that the throttle I5 is provided with a switch 27 which is closed when the throttle is opened. The closing of the switch 27 establishes an energizing circuit for the actuating coil of the switch S which may be traced from the positive terminal of the battery 88 through conductor 28, the switch 21, conductor 29, contact fingers 3| and 32 bridged by a segment 33 on the controller MC, conductor 3c, an interlock 35 on the switch P i, conductor 35, the actuating coil 31 of the switch S, conductors 38 and 39 to the negative terminal of the battery iii. The closing of the switch S connects the motors It and H across the generator 92 in series-circuit relation.

As explained hereinbefore, the closing of the switch GP to shunt the resistor 26 from the circuit for the field winding [6 of the generator I2 is delayed by means of an interlock on the switch S until after the switch S has closed, thereby causing the motors I0 and H to startat a recluced voltage of the generator 12. When the switch S closes, a circuit is established for the actuating coil of the switch GF which may be traced from a contact finger 4| on the controller MC through conductor 42, an interlock 43 on the switch S, conductor '14, the actuating coil 35 of the switch GF and conductors 33 and 39 to the battery l8. When the resistor 26 is shunted by the switch GF, the generator voltage increases gradually because of the large inductance of the .generator field. In this way, the tractive effort of the motors builds up gradually.

manner, full voltage of the generator I2 is not applied to the motors until after the completion of the transition from series to parallel operation, thereby ensuring smooth operation of the locomotive during the transition period.

From the foregoing description, it is apparent that I have obtained the advantage of smooth acceleration of a diesel or gas-electric locomotive in a relatively simple manner since the desired operation of the locomotive is obtained by means of interlocks actuated by the switches which are usually provided for establishing the desired motor connections. Therefore, the present system is simple in operation and may be provided on a locomotive by the addition of a small amount of equipment to the apparatus usually installed on diesel-electric locomotives.

Since numerous changes may be made in the above-described construction and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all matters contained in the foregoing description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In a motor control system, in combination, a pair of motors, a generator for supplying current to the motors, an engine for driving the generator, a plurality of switches individually operable in sequential relation for connecting the motors to the generator in either series or parallel-circuit relation, a controller for controlling the sequential operation of said switches,

means for varying the excitation of the generator,

The acceleration of the locomotive continues until the throttle I5 is wide open. A higher speed is obtained by moving the controller MC to the parallel position, thereby opening the switches GF and S and closing the switches PI and P2 to connect the motors l0 and H in parallel-circuit relation. The energizing circuit for the actuating coil of the switch Pl may be traced from a contact finger G6 on the controller MC through conductor 41, the actuating coil 43 on the switch PI and conductors 38 and 39 to the battery It. The energizing circuit for the coil of the switch P2 extends from the conductor 41 through an interlock 49 on the switch S, conductor 5i, the actuating coil 52 of switch P2 and conductors 38 and 39 to the battery l8.

It will be noted that the reclosing of the switch G1 to shunt the resistor 26 from the circuit for the field winding I6 of the generator [2 cannot take place until after the switch P2 is closed. The energizing circuit for reclosing the switch GF extends from conductor 34 through an interlock 53 on the switch P2, conductors 54 and 44, the actuating coil 45 of the switch GF and conductors 38 and 39 to the battery I8. In this and interlocking means actuated by said switches for controlling the operation of said excitation varying means.

2. In a motor control system, in combination, a pair of motors, a generator for supplying current to the motors, an engine for driving the generator, switching means for connecting the motors to the generator in series-circuit relation, additional switching means for connecting the motors to the generator in parallel-circuit relation, a controller for operating said switching means in sequential relation, interlocking means actuated by said switching means for preventing them from closing simultaneously, means for varying the excitation of the generator, and additional interlocking means actuated by said switching means for controlling the operation of said excitation varying means.

3. In a motor control system, in combination, a pair of motors, a generator for supplying current to the motors, an engine for driving the generator, switching means for connecting the motors to the generator in series-circuit relation, additional switching means for connecting the motors to the generator in parallel-circuit relation, a controller for operating saidswitching means in sequential relation, interlocking means actuated by said switching means for preventing them from closing simultaneously, a resistor for controlling the excitation of the generator, a switch for shunting said resistor, and additional interlocking means actuated by said switching means for controlling the operation of said 0 switch.

TI-IELBERT L. WEYBREW. 

